Out of curiosity, how do bubbles affect the reading? On one hand, I understand the idea that, once the gas it out, you have more density, so you will theoretically get a higher gravity reading. On the other hand, if you take a reading while the sample is degassing, wouldn't that make the hydrometer more buoyant and therefore read "higher" when, in fact, it should be a lower SG?
For example, I take a hydrometer reading while I see some bubbles degassing from the sample. It reads 1.02. Since I am taking the reading during the degasssing, should I assume the SG is lower, say, 1.018 or so?